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SPHERESOFTHEEARTH • TheEarthhas4spheres: 2.ATMOSPHERE 3.HYDROSPHERE 4.LITHOSPHERE 5.BIOSPHERE
EARTH’SINTERIOR TheoutershelloftheEarthiscalledtheCRUST • ThenextlayeriscalledtheMANTLE • ThenextlayeristheliquidOUTERCORE • ThemiddlebitiscalledthesolidINNERCORE •
PLATES •TheEarth'ssurfaceismadeupofaseriesoflargeplates(likepiecesofagiantjigsawpuzzle). •Theseplatesareinconstantmotiontravelling atafewcentimetresperyear. •Plates'float'onthemoltenrockmagma.AsthecoreoftheEarthheatsupthematerialsinside,themoltenmagmaalsogetsheatedup.Theheatcausesconvectioncurrents,amovementofrisingandsinkingcausedbyheat,insidethemoltenmagma.
PLATEMARGINS •Theplacewheretwoplatesmeetisknownasplate margin/boundary. •Thereare3typesofplatemargins/movements: 3.DivergingPlateMargin 4.ConvergingPlateMargin
DIVERGINGPLATEMOVEMENTS •Placeswhereplatesarecomingapartarecalleddivergentboundaries. •whenEarth'sbrittlesurfacelayer(thelithosphere)ispulledapart,ittypicallybreaksalongparallelfaultsthattiltslightlyoutwardfromeachother. •Magma(liquidrock)seepsupwardtofillthecracks.Inthisway,newcrustisformedalongtheboundary. •Earthquakesoccuralongthefaults,andvolcanoesformwherethemagmareachesthesurface. •Forexample,divergencealongtheMidAtlanticridgecausestheAtlanticOceantowidenat
CONVERGINGPLATEMOVEMENTS Whentwoplatesmovetowardseachother,theywouldcollide.Thisiscalledaconvergentplatemovement. • Astheplatescollide,somecrustisdestroyedduetotheimpact,thereforethisconvergentboundaryisalsocalledadestructiveboundary. • •Examples: 4.thecollisionbetweenthe EurasianPlateandthe IndianPlatewhichisformingtheHimalayas. 5.subductionoftheNazcaPlate beneaththe SouthAmericanPlatetoform .
WHENANOCEANIC& CONTINENTALPLATESCONVERGE
WHENTWOOCEANICPLATES CONVERGE
CONSERVATIVEPLATE MOVEMENT •Atransformplatemovementisonewheretwoplatesslidelaterallypasteachother. •Thismovementisnotsmoothduetofrictionbetweentherocksofthetwoplates. •Whenthereissufficientbuildupofpressure,rocksintheplatesbreakandgetjerkedapart.Thisresultsinearthquakes.
HAZARDSASSOCIATEDWITH PLATES •MostEARTHQUAKESandVOLCANICERUPTIONSoccurinspecificareas,suchasalongplateboundaries.
EFFECTSOFEARTHQUAKES • Negativeeffectsofearthquakes: • Tremendouslossoflife. • Lossofproperty. Collapseoftransport–roads,railways,ports,bridges. • • Fire,landslides,floods. • Blockedroads Facilitiesdisrupted–electricity,water,medical. • • Tsunamis
VOLCANO AVolcanoisanopeningorruptureontheEarth’sSurfacewhichallowsmagma,rocks,gasesetc.tocomeoutfrombelowthesurface. • • CausesofVolcanicactivity: d) Divergingplates e) Convergingplates f) HotSpots g) Faults • ImportantTerms: • VentandFumeroles • Crater • Pyroclasticmaterial • Lavaflow • MagmaChamber • Coneshapedhill
TYPESOFMATERIAL-VOLCANO ThreetypesofmaterialsareejectedoutofaVolcano: •SOLIDS:ashparticles(<2mminsize);Lapilli(2–64mminsize);Volcanicbombs(>64mminsize) •LIQUIDS:Moltenmaterial–Magma,Hotwaterfromgeysersandhotsprings. •GASES:Water-vapour,carbonmonoxide,carbondioxide,sulphurdioxide,hydrogenchloride,hydrogenfluoride,
TYPESOFVOLCANOES • • • • Onthebasisofshapeandmaterialtheyaremadeof: ShieldVolcano:Gentleslopes, basalticlava,lowviscosity.Eg.Mt.MaunaLoa,Hawaii CinderVolcano:Steepslopes,>300metersinheight,made ofpyroclasticmaterial.Eg.Mt.Paracutin,Mexico Composite/StratoVolcano:Steepupperslopes&then l,eta lava&ash.Eg.Mt.Vesuvius, Onthebasisoffrequency: ActiveVolcano:whicheruptfrequently&caneruptanytime.Eg.Mt.MaunaLoa,Hawaii.DormantVolcano:whichhaveeruptedinhistorybuthavenoteruptedsincethen.Eg.Mt.Rainier,USA ExtinctVolcano:whichmayhaveeruptedearlierbutisnowalmostdead(>1000E
TYPESOFERUPTIONS • Therearefivemajortypesoferuptions: c)Hawaiian d)Strombolian e)Vulcanian f)Pelean g)Plinian
EFFECTSOFVOLCANO • PositiveEffects: • Negativeeffects b)Lossoflife c)Lossofproperty(economic loss) d)AirPollution(ash,smoke, gases,acidrainetc) b)Ashaddtothesoil fertility–farming c)Newmineralsmaybe discovered d)PromotesTourism e) f) e) f) g) Waterpollution Lahars(mudflowswithwater) Earthquakes Researchandeducationpurposes. GeothermalEnergy–renewableenergy. h)Increaseintemperature ofthearea